Not really an issue. Ok, it's not as great as other healers, but saving your 30 stacks for that 'oh ****' moment.... emergency scan, healing scan, rapid scan, healing scan, rapid scan, healing scan, rapid scan, emergency scan...... and thats if they took alot of damage AND continually taking damage.
Dont forget to use missile on cooldown for the +% to healing. As well as kolto shell.
Healing scan is also a HoT if talented with a +10% armor, dont forget missle adds a shield too.